Reptiles

Before the Scientific Revolution, any attempt to ascribe order to nature was largely rooted in the study of holy texts, rather than in the nature of minerals and organisms themselves. The development of natural history as an observational science in the seventeenth century changed this entirely and lives on to be a crucial element in the study of living organisms today.

It has become popular in the modern era to dismiss natural history as “mere” classification, lacking empirical methods, but this could not be further from the truth. Accurate classification is an essential element of understanding the natural world. There is not a more essential answer to the question “what is x?” than to give the classification of x, i.e. put it in relation to other living beings. Such an indefinite number of characteristics can be inferred by an organism’s taxonomic standing alone that this serves as a sort of shortcut to ripping individual organisms to shreds and painstakingly having to analyze and reanalyze the constituent parts of each individual organism. While an understanding of the anatomy of individuals within a species is of interest to some and has intrinsic value, the understanding of organisms in context with other similar and dissimilar organisms also has value. For those with questions unconcerned with the minutia of differences between individuals and who are focused with broader themes in evolution or organismal biology, a system of classification serves as a heuristic to understanding basic aspects of the organism at hand in relation to its own or other groups of organisms. Today, rather than defining natural groups by shared characteristics, these characteristics aid in the diagnoses of natural groups, which rather are defined by evolutionary relatedness. Still a need for the accurate classification of organisms persists.

Natural history as an observational rather than experimental science is not an outdated way of conducting zoology, ecology, or botany. Research lab settings are artificial and for those concerned with ethology, ecology, and observational field studies are crucial for comprehending the life history and behavior of animals and plants. Such observational studies have formed the bedrock of the modern understandings of these subjects. Even experimental studies themselves are inspired by observational studies after all.

Carolina Parakeet specimens are among the irreplaceable extinct specimens held in the Tetrapod Collection. (Photo Credit: Chelsea Hothem 2016)

Natural history museums and the specimens they contain also retain both intrinsic and practical value. Far from ‘mere’ cabinets of curiosities, natural history specimens serve as physical records of organisms, vouchers, from throughout history. The tags of these specimens usually record the location where the specimen was collected, the date, the stomach contents of the organism (for animals), pre-preparation measurements, the name of the collector, the cause of death, and many other bits of information that prove invaluable for research. Each specimen is comparable to a library book brimming with information that can inform future scientists on topics ranging from biodiversity, species distribution, the changes in species over time, impacts of humans over time, genetic information, historic climates, and conservation.

A young bluebird (Sialia sialis) that died after being entangled in this plastic. This is an unfortunate reminder that what humans do with their trash has repercussions for other species.This specimen was prepared by Tetrapod Curatorial Assistant, Grant Terrell and is now housed in the Museum of Biological Diversity’s Tetrapod Collection. (Photo: Grant Terrell, 2016)

A modern example of the utility of museum collections is the application of DDT and its effects on North American birds. Chemicals within DDT were responsible for the terminal thinning of eggshells in birds exposed to the pesticide. Not until contemporary eggs could be compared with eggs in museum collections, were scientists able to confirm why avian populations were suffering. If naturalists had not been consistently collecting eggs from North American bird species, humans may have continued using DDT without fully understanding its effects on non-targeted species. The value of a particular specimen only increases with time. This lesson can effortlessly be learned after only a single encounter with a specimen of a recently extinct species such as the Passenger Pigeon. Individuals within museum collections and the observations of naturalists are now all that remain for researchers with questions about such species. The advent of new technologies only increases the value of the work of naturalists such as Sir Hans Sloane. Researchers now sequence the DNA of specimens and compare it to that of modern individuals. It is unknowable what advances may further enhance the value of the study of natural history.

Thus it is very important to ensure preservation of specimens for future generations. Please support our efforts through our current fundraiser.

About the Author: Grant Terrell is a second year student at the Ohio State University who is currently double-majoring in Evolution & Ecology and History. He currently works as a Curatorial Assistant in the Tetrapod Collection of the Museum of Biological Diversity and focuses on Ornithology.

Last time we talked about how birds spend the winter, many of them leaving our state and moving south. But what do animals do that cannot fly or move long distances? How do lizards, snakes and turtles stay warm in the cooler temperatures? Birds are endothermic homeotherms, animals that keep a constant body temperature and maintain this temperature through metabolic processes. They face the problem of not finding enough food in winter to maintain their high body temperatures. When our fields are covered with snow, frost has turned the soil rock-hard and trees and bushes have lost all leaves and berries there is not much left for birds to feed on (unless they rely on you filling your bird feeder all winter and some of them do take that risk).

Reptiles face an even greater problem, they not only have to worry about food but also about their body temperature dropping drastically, maybe even below temperatures that allow normal metabolic processes. As ectothermic poikilotherms they gain heat from the environment and their body temperature changes with the surrounding temperature. You have probably seen lizards and snakes basking in the sun, particularly early on a cool morning in spring or fall. The last mornings were good examples with temperatures in the low forties but the sun quickly warming up the ground. These reptiles are also warming up and most of the time, when disturbed, are only slowly moving out of harm’s way. Their sensory cells and muscles are not working well at low temperatures.

An Eastern garter snake Thamnophis sirtalis basking in the sun

So how do cold-blooded animals survive winter’s cold which comes with reduced daylight hours and little sun – at least in Ohio? Let’s look at turtles, for example. Do you remember the big snapping turtle that spent the summer in your garden pond and fed on all living creatures that would come close?

A common snapping turtle

Snapping Turtle Chelydra serpentina OSUM reptiles 976

The recent colder temperatures have slowed the turtle’s metabolism. This means that it needs less oxygen and food. Once the water temperature drops (not quite yet, as you may have seen fog over your pond in the early morning indicating that the pond water and immediate air are warmer than the surrounding cool air, and the water appears to steam), the turtle will look for a sheltered area of your pond and descend to the bottom of it. It will hibernate below the frost line where the water temperature stays constant and the turtle’s metabolism can adjust to a constant rate. (Snapping turtles are actually hardy creatures that have been reported to be active and moving around below the ice on frigid winter days).

Early morning fog (CC0 public domain)

The turtle slowly uses up its energy reserves and keeps breathing. To sustain the latter turtles have evolved to breath directly through their skin and retrieve oxygen from the water itself. Amphibians survive the same way.

How did we find out about this amazing behavior of hibernation in reptiles? Imagine you are a scientist observing turtles, you watch them in spring, summer and fall and then they suddenly disappear until they resurface in spring. Your first thought may be that they die in fall, maybe right after they had laid some eggs which somehow survive the winter and develop into new life in spring. But the animals that you observe in spring are not young ones. You collect a few and take them to your local natural history museum, where you find many more specimens in the collection and you can compare them with each other. It turns out they are indeed adults and must have survived the winter.

Turtle specimens in ethanol

A quick search of our collection database reveals that of the 609 specimens of some 35 species in the turtle family Testudines only one specimen was found alive in February, a Mexican mud turtle Kinosternon integrum that Ted Cavender, then curator of fishes at OSU, collected in a stream 20 miles west of El Naranjo along Highway 80 in San Luis Potosí county, Mexico on Sunday February 7th. The year was 1971. This was two days after the crew of Apollo 14 started exploring the moon, but probably more important for the turtle, it was a very warm February, with temperatures in the low eighties and even into the nineties in southern California (Wagner 1971 – Weather and Circulation of February 1971). Maybe the turtle was fooled into an early arrival of spring? If such warm weather continued over several weeks, maybe the water temperature rose, increasing the metabolism of the turtle which would use up its energy reserves much faster and would require it to resurface to replenish its reserves. Given the exact data on location and date with this specimen we could investigate further. If the scenario I laid out above is true, this turtle may even give us a hint at what may happen to turtles across the USA should temperatures continue to rise due to recent climatic changes. I hope you can see how a museum specimen can be a treasure trove of information helping us to understand today’s fauna and in some cases may even help us predict changes into the future.

Mexican mud turtle Kinosternon integrum

We are still in the middle of our campaign to raise funding for the purchase of a new cabinet for our not-so-lucky animals, species that went extinct because of over-hunting, habitat loss and other mainly human-caused changes in their environment. Please help us spread the word and donate today.

Cool fact: The oldest turtle specimen in our collection is a common musk turtle from Franklin Co, Ohio collected in June 1896.

The oldest specimen collected in 1896, a common musk turtle Sternotherus odoratus

If you don’t think snakes can be cute, perhaps you’ve just never seen a smooth green snake (Opheodrys vernalis). A cousin of garter snakes and rat snakes, the smooth green snake is in the Colubridae family. They are found throughout the continental United States, southern Canada, and northern Mexico. The smooth green snake looks similar to the rough green snake (O.

aestivus) but can be distinguished by its namesake smoother scales and more terrestrial lifestyle. This slender snake only grows to around one to two feet (30-60 cm) long. Since they are small and non-venomous, they’re harmless, unless you’re a small invertebrate. Much like The Lion King’s Timon and Pumbaa, smooth green snakes primarily eat insects, spiders, worms, and snails (1,2,3,5).

From June to September, the female smooth green snakes lay eggs in burrows under logs, rocks, or vegetation. Multiple females have been observed depositing eggs in one communal nest site. The eggs can hatch anywhere from four to thirty days later. The incubation period is thought to vary greatly due in part to the female’s ability to retain the eggs in her body, which helps speed their development. Born with no need for parental care, hatchlings grow quickly and can triple in size within their first year of life (1,2,3).

From November to March, smooth green snakes spend the winter hibernating. Hibernacula (places where animals hibernate) can be under rocks and logs or inside anthills and abandoned rodent burrows (1,2,3). Individuals frequently hibernate together and have even been known to share hibernacula with other species including their close relative the garter snake (genus Thamnophis) or even skinks (genus Plestiodon) (1).

Year-round, this reptile prefers to live in moist and grassy habitats in prairies or near marshes and lakes, although they can sometimes be found in drier habitats like forests. As prairies and marshes have given way to neighborhoods and shopping centers, the wildlife that lived in those habitats has also disappeared (1,2,3,5). Unfortunately, the smooth green snake is no exception. In Ohio, the smooth green snake is endangered and is only encountered in the extreme southwest of the state (if at all)(5). However, the species as a whole is considered stable and smooth green snakes are still populous in other parts of their range for now (4).

From the massive wingspan of the American White Pelican to the incredible size of the Eastern Hellbender, recently the focus has been on very large specimens from the Tetrapod Collection. So for this month’s post, I’d like to write about one more giant specimen we have and end the trilogy of the colossal species.

Our gigantic Leatherback Sea Turtle

With an average length of seven feet and an average weight of 2,000 pounds, the Leatherback Sea Turtle (Dermochelys coriacea) is the largest species of turtle on the planet. Leatherbacks are believed to have the widest global distribution of any vertebrate, meaning they can be found in any of the world’s temperate oceans. Like most other sea turtles, leatherbacks feast on soft bodied organisms such as jellyfish, squid, blue-green algae, etc… One unique trait of the Leatherback Sea Turtle is that it has the ability to maintain warm body temperatures in cold water. Reptiles are famously “cold-blooded” and can only heat up their bodies using their surroundings. However, Leatherback Sea Turtles seem to be able to generate and maintain their own body heat through adaptations such as their large body size, changes in blood flow and a thick layer of fat. The leatherback is the only sea turtle species that doesn’t have a hard bony shell. A leatherback’s top shell (carapace) consists of leathery, oil-saturated connective tissue that is almost rubbery to the touch. Even after decades of storage at the museum, oils are still leaking from the carapace of our specimen. For more general facts about the Leatherback Sea Turtle, visit the National Geographic’s website .

All seven species of sea turtles (leatherbacks included) are endangered, with some species even being classified as critically endangered (meaning they are facing an extremely high risk of extinction in the wild). There are a number of reasons for the turtles being in danger of extinction such as poaching, habitat loss, pollution, collisions with boats, people stealing turtle eggs, etc…

Just so you can get an idea of how large these turtles are, here is Tetrapod Volunteer Abby Miller sitting beside our specimen

However, a paper by Lewison, Freeman and Crowder (2004) discusses another reason for the turtle’s decline. When fishermen throw out their nets in hopes of catching fish such as sardines or mackerel, they often end up catching many other animals such as dolphins, sharks, and sea turtles by mistake. This is known as bycatch, and many times these other non-target species will see drastic reductions in population because of it. I know it may be hard to picture an animal as massive as the Leatherback Sea Turtle getting caught in these nets, but these are very large nets that are often used for large groups of fish. When a turtle becomes entangled in the net, they can drown or suffer external injuries while struggling to get out. This study aimed to determine what effect bycatch has on leatherback numbers and what they found was shocking. According to their research, 50,000 leatherback sea turtles were caught as bycatch in the year 2000. This research and other investigations like it, have led to some new policies regarding the use of drift nets. According to the American Bird Conservancy, Russia has banned the use of drift nets due to the harm they cause to seabirds, marine mammals and other aquatic species such as sea turtles.

As I had mentioned earlier, all sea turtle species are endangered and the Leatherback is no exception. This phenomenon of bycatch illustrates how much damage commercial fishing can do to the oceans’ ecosystems and how we should think of ways to alleviate this problem. There has already been much success in reducing bycatch by using specially designed nets that help free any turtles that become ensnared, and many fishermen have begun to employ these nets in their everyday work. These animals are unique due to their immense size and awe-inspiring presence, to lose them would be a major defeat for conservationists worldwide.

Part of the Tetrapod collection holds preserved reptiles, most of which represent native Ohio species along with several species from other parts of North America. To find a Species of the Month, I ventured down the aisles of shelves with jars of snakes, lizards, turtles, and tortoises. When I saw this Timber Rattlesnake, one of our collection’s most impressive reptilian specimens, I made my choice. I chose an animal that is feared, and misunderstood, by many.

Attaining an average length of about 3-4 feet, the Timber Rattlesnake (Crotalus horridus – a frightening name for an animal that rather avoids than seeks conflict) is a fairly large snake. Like most snakes, Timber Rattlesnakes are feared by a lot of people who don’t understand them well enough. It’s important to remember that snakes such as the Timber Rattlesnake don’t seek out conflict with humans, but rather try to avoid it. A part of the fear people have for snakes comes from common misconceptions, which these facts below will hopefully clear up.

Their range stretches throughout most of the temperate forests in the Eastern United States and Canada, however they can no longer be found in Maine and Ontario. Here in Ohio, they can really only be found at the southern end of the state. Timber Rattlesnakes will mate during the spring and fall with the females giving birth to anywhere from 4-14 young during the late summer. What’s interesting about rattlesnakes (Timbers included) is that they give birth to live young, which is very unusual for a reptile. Many reptiles, just like birds, usually lay eggs from which their young hatch after some incubation time. When the snakes feel threatened, Timber Rattlesnakes will rattle their iconic tails as a warning to potential predators that get too close. These snakes eat a wide assortment of small mammals and can sense their prey using special heat sensory organs that are located on their heads. These sensory organs are known as loreal pits and are a characteristic common to all members of the pit viper family, which includes rattlesnakes.

When Timber Rattlesnakes deliver a bite, deadly venom will be injected through the snake’s hollow fangs and into the victim. A common misconception is that snakes are poisonous; when in actuality they are venomous. Venomous organisms directly inject venom into the victim whereas poisonous organisms have a poisonous substance covering their body making them dangerous only when eaten or touched. Learn more general facts about Timber Rattlesnakes from an Ohio Certified Volunteer Naturalist.

Quite a bit of research has been done on these snakes, a few years ago Rokyta et al (2013) reported that components of their venom seem to have changed. Some species of snakes (Timber Rattlesnake included) have undergone a dramatic shift in the lethality, and composition of the venoms they produce. Traditionally, Timer Rattlesnakes produced a hemorrhagic type of venom, which causes the snake’s victims to bleed to death from the inside out (visit the Snakes and Spiders web site for a full description of how snake venom works). However, this study shows that, at the southern end of their range, Timber Rattlesnakes are beginning to develop a bite consisting of neurotoxin venom. Neurotoxins attack the victim’s central nervous system resulting in cardiac arrest and trouble breathing thus making it much deadlier than hemorrhagic toxins. Similar research on the evolution of snake venoms is being done at the molecular level by researchers in the Gibbs lab here at OSU.

Timber Rattlesnakes are amazing animals that encompass both beauty and lethality. Their status as a top predator has even landed them a place in history as the species of snake that appears on the “Don’t Tread on Me” flag. While these are highly venomous creatures, it’s important to remember that they just want to be left alone and do their best to avoid conflict with humans. Should a Timber Rattle snake bite you or someone you are with then please follow the procedures outlined by the Wild Backpacker to ensure a safe and speedy recovery from any venom related injuries. If you ever encounter a Timber Rattlesnake NEVER try to approach or pick it up, instead leave it alone and in turn it will leave you alone. Timber Rattlesnakes remind us that sometimes it best to admire natural beauty from a distance.

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